The long-term objective is to determine the cellular events of an operant-conditioning learning paradigm. A well-studied model system, based on training of joint position and/or frequency of discharge of identified tonic motor neurons of locusts will be utilized. It is probable that attention, which is desirable or essential for learning in humans, represents the release of a modulator biogenic amine, which promotes long-term changes in neuronal properties. Neither the basic cellular mechanisms nor the action of such a modulator are known for any instance of operant conditioning. The preparation provides a means for testing the possible involvement of the locust equivalent of the important human modulator, the catecholamine adrenaline, wich is the monoamine octopamine (OCT). The activity of the neurons synthesizing OCT in the third thoracic ganglion will be recorded intracellularly during the conditioning. The output and properties of identified motor neurons whose cell bodies and dendrites are located in this ganglion will be followed and correlated with activity in specific octopaminergic neurons. If a correlation between them is observed, compared with random and yoked controls, the effects of OCT locally-iontophoresed onto motor integrating regions on learning, will be tested. OCT-blockers will be iontophoresed into the same regions and their effect on training determined. Even if OCT turns out not to be essential, the experiments will extend our knowledge of the cellular neuronal events associated with operant conditioning. Octopamine is present in relatively large quantities in normal human brains, yet is functions there are totally unknown.